Detection of contaminants in food

ABSTRACT

A food contamination detector. The food contamination detector comprises a first bar code symbol coded to identify a food product by a bar code reader, a second bar code symbol coded to identify contaminated food by a bar code reader, and an indicator printed onto a substrate which changes color when food is contaminated and causes the first bar code symbol to be unreadable by a bar code reader and causes the second bar code symbol to become readable by a bar code reader.

This is a continuation application of U.S. application Ser. No.09/052,374 filed Mar. 31, 1998, now abandoned which is a continuation ofU.S. Application Ser. No. 08/758,205 filed Nov. 26, 1996, now abandoned,which is a continuation-in-part of U.S. application Ser. No. 08/584,984,filed Jan. 11, 1996, now abandoned which is a continuation of U.S.application Ser. No. 08/197/297 filed Feb. 16, 1994, now abandoned,which is a continuation-in-part of U.S. application Ser. No. 08/064,521filed May 19, 1993 now U.S. Pat. No. 5,306,466 issued Apr. 26, 1994, andthis application claims the benefit of U.S. Provisional Application Ser.No. 60/027,412, filed Sep. 30, 1996. The above mentioned applicationsare hereby incorporated by reference as if fully set forth herein.

FIELD OF THE INVENTION

The present invention relates to detection of the presence of toxiccontaminants in food.

BACKGROUND OF THE INVENTION

Over the past several years there has been increasing concern over thesafety of our food supply. Contamination of food can come from a varietyof sources and the type of contamination possible is often dependent onthe food involved.

Most animal derived food products, such as raw meat, are exposed to thepossibility of contamination before, during or after processing. Suchcontamination comes from, for example, contact with faecal matter at theslaughter house, from handlers of the food products at any stage of theprocessing of the food products or from toxins, both naturally occurringand man-made, present in the environment where the food was grown orprocessed. In most cases, contamination is minor and, if the food isprepared properly, is not a serious threat to the consumer. However,while the contamination of food is generally low, i.e. few bacteria pergram of the food, if the food is not stored under satisfactoryconditions or stored for long periods of time, contaminants, such asbacteria, grow to become a serious threat to the eventual consumer ofthe products. Even if the food products reach the market in anacceptable condition, subsequent treatment by the consumer may lead tothe development of serious contamination of the food.

A number of incidents and factors have lead to the growing concern overthe food supply. These include:

raw chicken and egg products have been found to be contaminated withSalmonella and inadequate cooking of such products has led to seriousillness or death of persons who have consumed the contaminated products;

inadequately pasteurized milk products have been found to becontaminated with Listeria which has lead to serious illness or death ofconsumers of the products;

a highly toxic strain of E. coli has lead to the death of several peoplewho consumed prepared beef products which had been inadequately cooked;

a number of toxins are known, such as ciguatoxins, which contaminatefish. These toxins are not inactivated or destroyed by cooking and sotheir presence in fish is a threat to any consumer of the product;

shell fish, such as oysters, concentrate any contaminants present in thewater in which they grow and, since they are frequently eaten raw, posea threat to the health of consumers; and

fish is increasingly eaten raw which adds to the possibility ofincreased outbreak of illness from water borne contaminants.

The only means the consumer has of determining if the food they purchaseis contaminated is by visual inspection and by smell. These are usuallyinadequate to detect contamination.

There is a need for a reliable way to detect if a food product purchasedby a consumer is fit for consumption. Any solution to this problemshould be relatively inexpensive and able to detect a number of agentscapable of causing illness. It should also be simple to “read” so that aconsumer, who does not have access to sophisticated testing equipment orspecialized knowledge, can readily determine if the products they havepurchased are free from contamination.

SUMMARY OF THE INVENTION

The present invention relates to a food contamination detector. The foodcontamination detector comprises an indicator bound to a substrate. Theindicator is in communication with juices from food which are to betested for the presence of a toxin.

A means for changing the color of the indicator when the toxin ispresent in the juices from the food is provided to indicate that thefood is contaminated. In one embodiment of the invention the means forchanging the color comprises a labeled antibody which dissociates fromthe substrate in the presence of a toxin. In another embodiment themeans for changing color comprises a labeled antibody which binds to thesubstrate in the presence of a toxin. In another embodiment the changein color results in a change in a bar code.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features and advantages of the present invention will bebetter understood by reference to the following detailed descriptionwhen considered in conjunction with the accompanying drawings in which:

FIG. 1 is a top view of a packaged food product;

FIG. 2 is a bottom view of the packaged food product with a bar codedetector system;

FIG. 3 is a side sectional view of the packaged food product showing thebar code detector system in the package;

FIG. 4 is one embodiment of the bar code detector system of the presentinvention, prior to attachment to a food package;

FIG. 5 is a schematic diagram of a bar code reader for use in thepresent invention;

FIG. 6 is a side sectional view of another embodiment of the bar codedetector system in a package tray without food;

FIG. 6A is an enlarged view of part of FIG. 6;

FIG. 7 is a perspective view of the bottom of the liner of FIG. 6 withone component of the bar code attached;

FIG. 8 is a front view of the component shown in FIG. 7;

FIG. 9 is a front view of another component of the bar code detectorsystem of FIG. 6;

FIG. 10A is a front view of the components of FIGS. 8 and 9 as theyappear from the outside of the food package in the absence ofcontamination;

FIG. 10B is a front view of the components of FIGS. 8 and 9 as theyappear from the outside of the food package in the presence ofcontamination;

FIG. 11 is a side sectional view of another embodiment of a bar codedetector system in a package tray without food;

FIG. 12 is a perspective view of a liner for use in a variation of thebar code detector system of FIG. 11;

FIG. 13 is a perspective view of a carcass indicator strip incorporatingprinciple of the invention prior to reaction with toxins; and

FIG. 14 is a perspective view of the carcass indicator strip of FIG. 13after reaction with toxins.

FIG. 15 shows a two bar code detector system which has not detected foodcontamination.

FIG. 16 shows a two bar code detector system which has detected foodcontamination.

DETAILED DESCRIPTION OF THE SPECIFIC EMBODIMENTS

The present invention uses an indicator which may be in the form ofwords, symbols, a bar code, or part of a bar code that identifies theproduct at point of purchase, sale, or distribution as a detector systemfor toxins and other contaminants that may be present in food products.As used herein toxin means chemicals or pathogenic organisms which maybe transferred from food to the consumers of the food, or other agentswhich may be toxic or result in illness in the consumer of thecontaminated food products.

The invention is described in the context of bar codes because this iscurrently the prevalent way to identify food products, includinginformation about product type, quantity, price, unit price, and originin a machine readable manner. The invention is applicable, however, toother product identifying systems, machine readable and/or readable to ahuman. When the term “visible” is used herein, it means visible orreadable by a bar code reader or other scanning apparatus.

The same reference numbers are used throughout the drawings to identifysimilar parts or elements.

Food products are often “mass produced” and sold at retail outlets, inprepackaged containers such as that illustrated in FIGS. 1-3. Typically,such packages include a styrofoam tray 10 which contains the foodproduct 12; the tray and food are sealed in a transparent plastic wrapmaterial 14 and a liner 15 lies between food product 12 and the insidebottom of tray 10. A bar code 16 is used on the products for scanning atthe check-out register (FIG. 5), to reduce errors in totaling purchasesand for stock control. The bar code comprises a series or pattern ofbars which represent a number, identifying the product. In the practiceof the present invention the product identifying system, e.g., the barcode, also serves the purpose of detecting toxins in the food products.

In the embodiment of FIGS. 1-3, a bar code 16 is printed on atransparent membrane or substrate 20. One side of substrate 20 has aself-adhesive surface for attachment to the interior of tray 10 and theother side of substrate 20 has printed on it bar code 16. The bottom ofstyrofoam tray 10 has a rectangular hole 18. Hole 18 is covered by awindow 21 formed by a transparent sheet of material such as MYLAR® (atrademark of DuPont) using a suitable adhesive to seal the MYLAR to thestyrofoam material around the edge of hole 18. Hole 18 and window 21also serve as a collector 19 for liquids and juices from food product 12so the latter can come into contact with bar code 16. Substrate 20 canbe prepared with a peelable, disposable backing or protective releaselayer 22 (FIG. 4), which covers bar code 16 prior to its application toa package. At the site of packaging of food product 12, release layer 22is peeled off and the adhesive side of substrate 20 is placed on theinside surface of window 21 so that bar code 16 faces the interior ofthe package and is exposed to the juices of food product 12. Inconventional food packaging the entire liner is generally absorbent. Inthe practice of the invention, only a small portion 15 of the linerslightly larger than substrate 20 is absorbent; the remainder of theliner is preferably impervious to food juices so that most of the foodjuices are channeled to substrate 20. The absorbent portion 15 a ofliner 15 is positioned in tray 10 in alignment with substrate 20 tomaximize exposure of substrate 20 to the food juices. Instead of makinga portion of liner 15 absorbent, a hole could be punched out of liner 15and substrate 20 could be attached by adhesive to liner 15 around theedges of the hole. As an alternative to the described embodiment,substrate 20 could also serve as the window, in which case it would beattached to, cover, and seal hole 18 in tray 10.

The bar code is formed by labeled antibodies bound to antigens. Thelabeled antibodies function as an “ink” and are “printed” in a bar codepattern on the transparent substrate 20. First, the antigens are boundto the entire surface of substrate 20 or the portion of its surface onwhich the bar code is to be placed. Then, the bar code is applied to theantigen coated surface of substrate 20 by a bar code printer, using thelabeled antibody as the ink. Preferably, bar code 16 serves the normalproduct identifying function of a bar code, i.e., it represents price,price per unit, type of product, origin, and quantity or weightinformation. As illustrated in FIG. 5, food packages carrying the barcode detector system 16 are passed under a bar code scanner or reader 24mounted on a counter 25 at the point of sale to read the productinformation in the usual way. A store computer 26 processes thisinformation to totalize the amount of purchase and to manage inventory.The bar code for use in the invention is prepared by irreversiblybinding an antigenic determinant of toxins or contaminants of interestto the transparent substrate. The antigenic determinant may be a smallportion of the toxin, which is specific for that toxin, it may be thetoxin itself, an analog of the toxin or other compound which is capableof “mimicking” the toxin, or pathogenic microorganisms, all of which arereferred to herein as “toxins.” Substrates suitable for binding thetoxin are well known in the art. If substrate 20 serves as window 21 itmust be impervious to the food juices. Suitable substrates includesubstrates such as those made from activated hydrophobic polyvinylidene,polyvinylidene difluoride, mixed esters of cellulose nitrate andcellulose acetate, hydrophobic polyvinylidene difluoride, hydrophilicpolyvinylidene difluoride, laminated and unlaminatedpolytetrafluroethylene, microfiber glass, cellulose and polypropylene.Once toxins are bound to the substrate other binding sites, which remainon the substrate, are blocked by contacting them with an “inert” bindingagent such as bovine serum albumin or other suitable blocking agent.

Once the toxin is bound to the substrate a labeled antibody, whichexhibits a specificity for the toxin, also referred to herein asanti-toxin, is bound to the toxin. Antibodies suitable for use in thepresent invention include monoclonal and polyclonal antibodies. Thepreparation of such antibodies, specific for a desired toxin, are wellknown in the art. In some cases it may be necessary to conjugate thetoxin to a protein to “mask” the toxicity of the antigen. Otherwiseinjection of the toxic antigen may result in the death of the animal inwhich the antibodies are to be prepared. Methods of conjugatingcompounds are well known in the art and one such method is described byHokama et al., Mycotoxins and Phycotoxins 188, A Collection of InvitedPapers at the Seventh International IUPAC Symposium of Mycotoxins andPhycotoxins, Tokyo, Japan 1988, pp. 303-310 (Elsevier SciencePublishers, Amsterdam), which is incorporated herein by reference.

In one embodiment of the present invention the antibody is labeled witha colored latex bead. The preparation of antibodies labeled with coloredlatex beads is well known in the art. Such labeled antibodies may beprepared by diluting latex beads in a solution such asphosphate-buffered saline (8.1 mM Na₂HPO₄, 1.5 mM KH₂PO₄, 137 mM NaCl,1.6 mM KCl) and mixing the solution gently to suspend and distribute thelatex beads in the solution. Preferably, about a 10% (wt/v) suspensionof latex beads is diluted about 1:100, to give a suspension of about0.1% (wt/v) latex beads. An antibody solution is added to the latex beadsuspension. Preferably, about 0.3 to about 0.6 mg of antibodies areadded for each mg of latex beads, however, this ratio will varydepending on the specificity and sensitivity of the antibody preparationand the type of support being used. The amount of antibody to be usedfor the preparation of labeled antibodies is derived experimentally,using different dilutions of the antibody preparation. After addition ofthe antibody, the solution is gently mixed and incubated at about 4° C.for about 16 to about 20 hours. At the completion of the incubation, thelabeled antibodies are washed with phosphate-buffered saline, and thesensitivity and specificity of the labeled antibody preparation aretested.

The sensitivity and specificity of the labeled antibodies are tested bycoating a substrate with a preselected amount of toxin. When contactedwith the labeled antibody, the labeled antibody binds to the toxin,resulting in the development of the desired color on the substrate. Thecolor which develops will not be washed off by rinsing in a solutionsuch as phosphate-buffered saline. Binding of the antibody to the toxinresults in the development of color for the bar code pattern forming abar code detector system named by the owner of this invention the SIRABART™ system. In effect, the labeled antibodies act as a type of “ink”so the bar code pattern can be visualized.

In use with raw meat products, the bar code detector system is exposedto juices from the meat. The juices collect in the collector and come incontact with the bar code detector system. If a toxin is present in thejuices, the antibodies will release from the bar code pattern and bindto the toxins present in the juices, thus altering or destroying the barcode pattern. Such antibody type assays are in and of themselves wellknown in the art and are referred to as competitive assays. A consumercan detect the presence of the toxin in the food product by a visualinspection of the bar code. If the consumer does not notice thealteration of the bar code, it is detected by bar code reader 24 at thecheckout counter (FIG. 5) because store computer is configured to emitan alarm to warn that a altered bar code has been detected. Thecontaminated products can then be replaced with non-contaminatedproducts.

A labeled antibody is one means of indicating the presence of a toxin orother contaminant in the juices of a food product. Those skilled in theart will be aware of other indicators such as chemical indicators, whichare useful in the practice of the present invention. Instead ofdestroying the bar code, the bar code could be altered in some otherway, e.g., by change of color, depending on the nature of the indicatingsystem. In general, the alteration of the bar code is detectable by thebar code reader so contamination of products can be automaticallydetermined by the electronics. Thus, the invention presents a format orvehicle to utilize existing toxin or contaminant indicating systems moreeffectively. The owner of this invention has named this format FOODSENTINAL™, a contaminant interdiction system.

The bar code reader can also be used to indicate whether packagedproducts are in satisfactory condition at the time they left thesupplier. If contaminated products are detected in the processingstream, the supplier can find out the source of contamination andimplement remedial steps to ensure that the source of contamination iseliminated.

The same toxin could be used for all the bars of the bar code or one ormore toxins could be used for different bars. In this way a number ofcontaminants or toxins, that are commonly associated with a particularfood, can be detected by a single bar code. The bar code would not onlyindicate that the food was contaminated but would also indicate the typeof contamination.

In another embodiment of the present invention shown in FIGS. 6-10, thecontamination indicator is incorporated in a bar code having twocomponents—one component inside the package and another componentoutside the package. A substrate 28 is attached to the bottom of a liner30 having an absorbent portion 30 a aligned with substrate 28. Portion30 a of liner 30 is an absorbent material that draws juices and otherfluids away from the meat to the surface of substrate 28. Substrate 28is preferably pervious to the juices of the food product, but it doesnot need to be transparent. The position of substrate 28 on liner 30 isprecisely set. As illustrated in FIGS. 7 and 8, one component of the barcode comprises visible indicator elements 27 and 29 printed on theexposed surface of substrate 28. Indicator elements 27 and 29 mayinclude a bar, a symbol, letters, or a combination thereof. In theillustrated embodiment indicator element 27 comprises a bar, given thetrademark SIRA BART™ by the owner of this invention, and indicatorelement 29 comprises the word “NOT”. Indicator elements 27 and 29 areprinted on substrate 28 using labeled antibodies as “ink”, as describedabove.

In this embodiment, the bottom of styrofoam tray 10 has a window 21formed by a transparent sheet of material such as MYLAR® (a trademark ofDuPont) using a suitable adhesive to seal the MYLAR to the styrofoammaterial. The liner and tray are designed so the liner can be preciselypositioned in the bottom of the tray. For example, liner 30 could bedimensioned so that when it is placed in tray 10 it fills the bottom ofthe tray with substrate 28 in register with window 21. In this way, theclose fit between liner 30 and tray 10 serves to insure that indicatorelements 27 are precisely positioned with respect to the secondcomponent of the bar code, which is placed on the exterior of the bottomof tray 10 and wrap material 14. Alternatively, ridges (not shown) couldbe molded into the inside bottom surface of tray 10 to position liner 30precisely and hold it in place.

As illustrated in FIG. 9, the second component of the bar code detectorsystem comprises a word 35 and a plurality of bars 31 printed on anopaque substrate 32 with ordinary ink and cut out sections 33 and 34 diecut from substrate 32. Section 33 is smaller than bar indicator element27. Section 34 is larger than word indicator element 29. Bars 31 performthe normal product identifying function of a bar code, i.e., theyrepresent price, unit price, type of product, origin, and weight orquantity. Substrate 32 has the same dimensions as window 21 and isplaced on the outside of wrap material 14 so substrate 32 coincides withwindow 21. As a result, the position of substrate 32 is precisely setrelative to substrate 28 so that indicator elements 27 and 29 arealigned with cut outs 33 and 34, respectively, and are normally visiblefrom outside the package. Indicator element 27 completely fills cut outsection 33 and indicator element 29 fits totally within cut out section34. In the illustrated embodiment, word 35 is “CONTAMINATED”.

When substrates 28 and 32 are aligned, the first and second componentsfit together to form the bar code. As illustrated in FIG. 10A, the words“NOT CONTAMINATED” are visible from the exterior of the package andindicator element 27 and bars 31 can be read by a bar code reader whenno contaminants are present in the food juices inside the package. Whencontaminants are present, the labeled antibodies from which indicatorelements 27 and 29 are formed react with the toxin and are removed fromthe substrate 28. As illustrated in FIG. 10B, this leaves only word 35and bars 31 visible. In the absence of element 27, the bar code readersenses that the bar code is “defective” and in the absence of element 29humans can visually observe that the contents of the package is“CONTAMINATED”.

Since it is desirable to detect different toxins in different foodproducts, indicator element 27 could be placed in different locations onsubstrate 28 depending upon the toxin to be detected and cut out 33could also be placed in different locations on substrate 32 dependingupon the toxin to be detected so it is aligned with the locations onsubstrate 28.

The described two component bar code detector system can be used togreat advantage with the conventional bar code applicator machines usedto mark food products in super-markets. Such machines have a conveyor onwhich wrapped food packages are transported past a weighing station anda bar code label application station into a temporary storage bin. Atthe label application station a label carrier roll is feed past aprinter where the product information is printed on the bar code labels(substrate 32) and under a blade where the bar code labels are releasedfrom the carrier and picked up by one or more robot arms for delivery tothe packages. A worker punches a product identification code into a keypad. A controller calculates from the product identification code andfrom the weight the product information to be printed on the label suchas price, weight, unit price, and historical data, i.e., origin, andcontrols the printer to print the bar code pattern and alphanumericcharacters on the labels. The controller coordinates, i.e., times, theoperation so the labels are applied to the proper packages.

A preferred method will now be described for using the two component barcode with a modification of the conventional bar code applicatormachines used to mark food products such as meat, poultry, or fish, insupermarkets. In a central processing plant, indicator elements 27 and29 are printed on substrates 28 with a labeled antibody or othercontaminant detector as ink; then substrates 28 are mounted on liners 30in a precise relative position and packed in shipping cartons. Linersare so prepared in separate cartons for each of a number of differenttoxins or contaminants and tray sizes. The cartons are shipped to thesupermarkets or packaging facility where the food products are packagedin trays, wrapped, and bar code labeled with the bar code applicatormachine. The packaging operation takes place in the following order:

1. For each different toxin or contaminant, one of the correspondingliners is placed in a tray sized for the particular liner.

2. The food product is placed in the tray.

3. The food product and tray are covered with the wrap material.

4. The package is placed in a bar code applicator machine and theproduct identification code is entered through the keyboard.

5. The package is weighed in the machine and transported by the conveyorto the label application station.

5. The bar code applicator machine is modified to incorporate a labelcutting die or die set in the path of the carrier between the roll andthe printer. The die is adjustable in position and its position is setby the controller depending upon the particular product identificationcode. Each time a bar code label passes the die, the die is actuated bythe controller to form the die cut sections (33 and 34 in FIG. 9).

6. The printer is operated by the controller to print words 30 and bars31 on the bar code labels with ordinary ink.

7. The bar code labels are applied by the machine to a precise locationon the outside of the packages in alignment with:substrates 28 (FIG. 6).

In summary, the first component of the bar code, which requires tightmanufacturing controls, is produced at a central processing plant. Atthe supermarket, workers without any special skill can reliablyincorporate the first component into food product packages and add thesecond component of the bar code in the usual way, i.e. with a bar codeapplicator machine, or manually. The only special training for theworkers at the supermarket is the proper selection and placement of theliner (30 in FIG. 6). If a worker makes a mistake in selection orplacement of a liner, bar 27 is not aligned with cutout 34 and the barcode reader senses the mistake. This provides a check to ensure that thecorrect toxin detecting bar has been used with the correct food product.

Substrate 32 is preferably opaque and white, or at least light in colorto create a strong contrast with the bar codes, which are preferablyprinted in a dark color. For this reason cutouts 33 and 34 are requiredso substrate 32 does not hide visual elements 27 and 29 of substrate 28.If sufficient contrast is otherwise available, substrate 32 can betransparent and the cutouts can be eliminated.

Instead of placing indicator element 27 and cutout 33 in differentlocations depending upon the contaminant to be detected, the locationcould remain fixed regardless of the type of contaminant and a visiblesymbol could be printed on substrate 32 near indicator element 27. Forexample, the letter “S” could be used for Salmonella, “E” could be usedfor E. coli, and “L” could be used for Listeria. This avoids having toincorporate an adjustable label cutting die in the bar code applicatormachine.

In the embodiment of FIG. 11, the contamination indicator is alsoincorporated in a bar code detector system having two components—onecomponent inside the package and another component outside the package.One component comprises a transparent bag 37 constructed from a bottompanel 36 and a top panel 38. Bag 37 is placed over hole 18 and thebottom panel 36 is secured to tray 10 by adhesive to seal hole 18 andform a window. Bottom panel 36 is fabricated from a substrate that isimpervious to the food juices. A first antibody against the toxin ofinterest is bound to an area of the interior surface of bottom panel 36identical in size and shape to or larger than hole 18. Top panel 38 isfabricated from a semipermeable membrane. The top and bottom panels aresealed together at their edges by use of an adhesive or other suitablemethod such as heat, to form a sealed bag, i.e., bag 37. Prior tosealing the bag a solution including a labeled second antibody againstthe toxin of interest is introduced into the bag. Although the first andsecond antibodies could be the same, they are preferably different.Thus, the second antibody preferably recognizes different antigenicdeterminants on the toxin than the first antibody. The second antibodyis labeled with an indicator such as a colored latex bead so that theresultant labeled antibody is of a large size. The labeled antibody,present in the solution, is at a dilute concentration so that light willreadily pass through the solution and so that little or no color isdiscernable.

The semipermeable membrane has a pore size which is large enough toallow the toxin of interest to enter the bag, but which is small enoughto prevent the labeled antibody from leaving the bag. Such membranes arewell known in the art and are commercially available in a variety ofpore sizes. The pore size of the semipermeable panel is selected so thatthe toxin of interest will pass through the semipermeable panel to theinterior of the bag.

When a toxin is present in the juices of a meat product packed in thetray, the toxin passes into the bag through semipermeable panel 38 andbinds to antibodies bound to panel 36. The toxin also binds to thelabeled second antibody present in the solution in the bag. As a result,panel 36 becomes colored by the sandwich assay of the first antibody,the toxin, and the labeled second antibody, thereby indicating thepresence of a toxin in the juices.

The second component comprises bar code 16 printed on substrate 20,which is a transparent material such as MYLAR®. Substrate 20 is placedover hole 18 on the exterior of the met tray, and preferably outsidewrap material 14. When a toxin is not present in the juices panel 36remains clear and the bar code can be easily read against the clearbackground. When a toxin is present in the juices, the toxin binds topanel 36 and to the labeled antibody such that the substrate backgroundbecomes densely colored. In a preferred embodiment the color of thebeads used is black and the uncolored background is white or clear. Thedense color of the first component prevents the bar code of the secondcomponent from being distinguished from the background by the bar codereader. This effectively obliterates or changes the bar code andindicates that the food contained in the package is contaminated.

A variation of the two component bar code detector system of FIG. 11 ispartially illustrated in FIG. 12. Panel 36 is secured to the undersideof liner 30 using an adhesive or other suitable means of attachment. Theportion 30 (not shown) of liner 30 covered by panel 36 is an absorbentmaterial that draws juices and other fluids away from the meat to thesurface of semipermeable panel 38 and serves to align bag 37 with hole18, in the manner described in connection with FIG. 6. The remainder ofliner 30 is impervious to food juices. The juices pass through thesemipermeable panel 38 and into the interior of bag 37. On the interiorof surface of panel 36 antibodies are attached as described above. Theantibodies are attached to a rectangular area 39 on the inside surfaceof panel 36 such that when the liner is placed in the food trayrectangular area 39 aligns with hole 18. Substrate 20 is attached to theouter surface of tray 10 after tray 10 has been covered with wrapmaterial 14. A bar code is printed on substrate 20 by the bar codeapplicator machine. The presence of toxins are then detected asdescribed above.

In another embodiment of the invention shown in FIGS. 13 and 14, asymbol such as a colored dot 42 is printed on a square porous substrate43. Substrate 43 is designed to be attached to the surface of a beefcarcass or other bulk food product to determine if the carcass iscontaminated. The “ink” used to print the dot is labeled antibodiesattached to toxin as described above. An opaque holder strip 44 coversand secures substrate 43 in place. Substrate 43 and hold strip 44comprise flexible material, which fits the contour of the carcass andkeeps substrate 43 in contact with the surface of the carcass. Acircular hole 47 is cut in the holder strip in alignment with substrate43, so that when the substrate and holder strip are attached to thecarcass, colored dot 42 is visible. If toxins are present in the meat ofthe carcass, the antibody becomes unbound from the surface of substrate43 and the dot disappears to indicate the presence of toxins in thecarcass. Holder strip 44 is attached to the carcass by use of stainlesssteel staples 46. The holder strip may also be used to display otheridentifying information, such as a bar code 48 and printed matter 50.Bar code 48 and printed matter 50 could be printed with ordinary ink.

A further embodiment of the bar code detector system is depicted inFIGS. 15 and 16. FIGS. 15 and 16 illustrate a two bar code foodcontamination detector system given the trademark GILBAR™ by the ownerof their invention. The GILBAR™ has a product identification bar code 52and a contamination detecting bar code 54. Additionally the GILBAR™ hasa contamination indicator area 56 which is outlined in FIG. 15 by blacklines for ease in visualizing the invention; however, in practice, theselines are not present so there is no interference with a bar codescanner or reader's ability to recognize product identification bar code52.

The GILBAR™ food contamination system alerts consumers and anyoneinvolved at any stage in food distribution using bar code scanners orreaders that a food item is contaminated as follows. In FIG. 15 theGILBAR™ has not detected contamination. Product identification bar code52 will be read by a bar code scanner of reader, whereas contaminationdetecting bar code 54 will not be read. As shown in FIG. 16, when thefood item becomes contaminated, the contamination indicator area 56 willchange color obliterating a portion of product identification bar code52 and adding an additional bar to contamination detecting bar code 54.Consequently, when the food product is contaminated, productidentification bar code 52 cannot be read by a scanner or reader,whereas contamination detecting bar code 56 will be read. Typically,data from bar code scanners is transmitted to a computer or somecentralized data collection for accounting, regulatory compliance ofother reasons. The ability to detect contaminated food products by barcode scanning creates an electronic record of whether or not a foodproduct was contaminated from the point of sale to the consumer backthrough the chain of distribution.

This system is particularly advantageous to alert consumers in a grocerystore or supermarket environment which typically uses fixed bar codescanners. Fixed bar code scanners which are often mounted in checkoutcounters generate a plurality of scanning lines in three dimensionalspace which is often referred to as the “sweet spot.” Supermarket orgrocery store checkout clerks typically orient the bar code so it facesthe scanner and sweep the product over the scanner window. This methodallows for rapid identification and pricing of products. Occasionally,when a bar code is not read the checkout clerk will type in the productidentification code to allow identification and pricing of the productwith the unreadable bar code. With the GILBAR™, when the productidentification code is readable the contamination detecting bar code isnot readable, and vice versa. Thus, when the food item is contaminatedthe product identification bar code will not be read, the contaminationdetecting bar code will be read, the consumer will be warned. Thiswarning could be an alarm or a warning that would appear on the checkoutregister display such as the words “adulterated”, “contaminated”,“spoiled”, or other such terms.

The product identification numbers may or may not be present. If theyare present, the indicator area 56 of the GILBAR™ would obliterate partof the product identification code rendering it incomplete to avoid theaccidental checkout of contaminated product. Additionally, the GILBAR™indicator area 56 could include a number which appears uponcontamination to complete a numeric code corresponding to the data codedby contamination detecting bar code 54. With these additional elements,a checkout clerk could not inadvertently price contaminated product whenbar code 54 is not recognized or read by the scanner.

The GILBAR™ is based upon the same principles previously describedherein. Instead of bars appearing in indicator area 56 the bars coulddisappear when a toxin is present. In this case one or more bars woulddisappear from product identification bar code 52 rendering the bar codeunreadable while an additional bar or other element would disappear fromthe contamination bar code area of indicator area 56 rendering thecontamination bar code 54 readable. Similarly, one or more digits of theoptional pricing code could disappear from the bar code label renderingthe code for product identification useless. Meanwhile, an extra numberor a colored background in the indicator area where the contaminationnumeric code is located could disappear exposing the numericcontamination code.

The GILBAR™ can be used inside the package as described herein withreference to FIGS. 1-5 with bars appearing or disappearing usingantibodies labeled with colored latex beads for the bar code “ink” on asubstrate 20. Alternatively, the GILBAR™ can be employed with a portionof the GILBAR™ inside the package and a portion outside the package asdescribed herein with reference to FIGS. 6-10. In the inside/outsidearrangement the bar code elements found in the indicator area 56 arelocated on substrate 28 with the remaining elements of bar codes 52 and54 aligned on the outside of the package with the interior indicatorbars. In another embodiment, the indicator area 56 and the contaminationdetecting bar code 54 are located inside the package while the productidentification bar code is located on the outside of the package. Thisarrangement enhances the ability to track the source of contaminationand still allows the processor, distributor and retailer to change theproduct identification bar code.

The present invention is not to be limited to the specific embodimentsshown which are merely illustrative. Various and numerous otherembodiments may be devised by one skilled in the art without departingfrom the spirit and scope of this invention. For example, with respectto the embodiments of the present invention illustrated in FIGS. 6-12,while the invention is described for use with antibodies against asingle toxin, mixtures of antibodies, against a number of differenttoxins could be used. With the use of different antibodies, multiple,different toxins which could be present in the meat sample can bedetected. Also, while the invention is described primarily in relationto obliterating a bar code, the antibody bound to the substrate couldalso be in the form of a symbol or wording which appears, or disappearsdepending on the type of antibody-toxin “assay” used. Such a symbol orwording could be read without the aid of a bar code reader. Also whilesome embodiments are described in conjunction with a liner, these barcodes could also be used in the absence of a liner. Similarly,embodiments described without a liner could be used in conjunction witha liner. The scope of the invention is defined in the following claims.

What is claimed:
 1. A food contamination detection system comprising:(a) a food package for containing a food product; (b) a bar code printedupon a transparent substrate; (c) a food contamination indicatorattached to said package and aligned with said bar code, whereby saidindicator changes color when food becomes contaminated and alters theappearance of said bar code.
 2. A food contamination detection system asrecited in claim 1 wherein the altered appearance of said bar code makesthe bar code unreadable by bar code reader.
 3. A food contaminationdetection system as recited in claim 1 wherein said indicator is achemical.
 4. A food contamination detection system as recited in claim 1wherein said indicator is in communication with the juices of the food.5. A food contamination detection system as recited in claim 1 whereinthe food package further comprises a tray and a transparent wrappingmaterial.
 6. A food contamination detection system as recited in claim 5wherein said indicator is located on said tray.
 7. A food contaminationdetection system as recited in claim 1 wherein: a second bar codeprinted upon the transparent substrate wherein the second bar code isaligned with the indicator, whereby said indicator changes color whenfood becomes contaminated and alters the appearance of the second barcode.
 8. The food contamination detection system as recited in claim 7wherein the altered appearance of said second bar code makes the secondbar code readable by a bar code reader.
 9. A food contaminationdetection system as recited in claim 1 wherein the indicator comprisesan antibody attached to a second substrate.
 10. A food contaminationdetection system as recited in claim 9 wherein the means for changingthe color of the indicator comprises a label attached to the antibodywherein the antibody dissociates from the second substrate in thepresence of the toxin.
 11. A food contamination detection system asrecited in claim 10 wherein the label comprises a latex bead.
 12. A foodcontamination detection system as recited in claim 9 wherein the meansfor changing the color of the indicator comprises a labeled antibodywhich binds to the second substrate in the presence of the toxin.
 13. Afood contamination detection system as recited in claim 12 wherein thelabel comprises a latex bead.
 14. A food contamination detectorcomprising: a food tray for containing food; and an indicator incommunication with juices from the food wherein the indicator comprises;a first anti-toxin attached to a transparent substrate; and a solutionin contact with the first anti-toxin attached to the transparentsubstrate, wherein the solution comprises a labeled second anti-toxinand wherein the labeled second anti-toxin becomes bound to thetransparent substrate rendering the substrate opaque in the presence ofa toxin in the juices from the food.
 15. A food contamination detectoras recited in claim 14 wherein the first anti-toxin recognizes anantigenic determinant on the toxin which is different from the antigenicdeterminant on the toxin recognized by the second anti-toxin.
 16. A foodcontamination detector as recited in claim 14 further comprising a barcode aligned with the transparent substrate.
 17. A food contaminationdetector as recited in claim 14 wherein the transparent substrate sealsa hole in a food tray.
 18. A food contamination detector as recited inclaim 14 wherein the solution comprising the second antibody is enclosedin a compartment.
 19. A food contamination detector as recited in claim18 wherein the compartment comprises a semipermeable membrane.
 20. Afood contamination detector comprising: an indicator strip in contactwith the juices from a packaged food, wherein the indicator stripincludes markings which are removed in the presence of a toxin; and abar code aligned with the indicator strip, wherein the combination ofthe presence of markings on the indicator strip and the bar code formsan intact visible indicator.
 21. A food contamination detector asrecited in claim 20 wherein the markings on the indicator strip areformed by labeled antibodies bound to a substrate.
 22. A foodcontamination detector as recited in claim 20 wherein removal of themarkings from the indicator strip results in a defective indicator. 23.A method of detecting contamination in food comprising: (a) attaching abar code printed upon a transparent substrate to a food package forcontaining a food product; (b) attaching a food contamination detectorto said package, wherein the detector comprises an indicator whichchanges color when food becomes contaminated, whereby said indicator isaligned with said bar code and alters the appearance of the bar codewhen the indicator changes color; and (c) detecting whether the bar codehas been altered by a change in the color of the indicator.
 24. A methodas recited in claim 23 wherein the food contamination detector comprisesan antibody attached to a second substrate.
 25. A method as recited inclaim 23 wherein the change in the appearance of the bar code makes thebar code unreadable by a bar code reader.
 26. A method of detectingcontamination in food as recited in claim 23 wherein said indicator is achemical.
 27. A method of detecting contamination in food as recited inclaim 23 wherein said indicator is in communication with the juices ofthe food.
 28. A method of detecting contamination in food as recited inclaim 23 wherein the detection is performed by use of a bar code reader.29. A method of detecting contamination in food as recited in claim 23wherein the detection is performed by visual identification.
 30. Themethod of claim 23 further comprising: attaching a second bar codeprinted upon the transparent first substrate, wherein the second barcode is aligned with the indicator, whereby said indicator changes colorwhen food becomes contaminated and alters the appearance of the secondbar code, and detecting whether the second bar code has been altered bya change in color of the indicator.
 31. The method of claim 23 whereinthe change in the appearance of the second bar code makes the second barcode readable by a bar code reader.
 32. A method as recited in claim 23wherein the means for changing the color of the indicator comprises alabel attached to the antibody wherein the antibody dissociates from thesubstrate in the presence of the toxin.
 33. A method as recited in claim32 wherein the label comprises a latex bead.
 34. A method as recited inclaim 23 wherein the means for changing the color of the indicatorcomprises a labeled antibody which binds to the substrate in thepresence of the toxin.
 35. A method as recited in claim 34 wherein thelabel comprises a latex bead.
 36. A method of detecting contamination infood as recited in claim 23 wherein the food package further comprises atray and a transparent wrapping material.
 37. A method of detectingcontamination in food as recited in claim 36 wherein said indicator islocated on said tray.
 38. A food product package comprising: a tray inwhich the food product lies; a transparent wrap covering the tray andthe food product; a first product information component disposed insidethe wrap so it is visible from the exterior of the package, the firstcomponent comprising a first substrate and one or more first visualelements printed on the first substrate with a material capable ofdetecting a pathogen or toxin; and a second product informationcomponent disposed outside the wrap, the second component comprising asecond substrate aligned with the first substrate without hiding thefirst visual elements and a plurality of second visual elements printedon the second substrate with a noncontaminant detecting material. 39.The package of claim 38, in which the first and second elements togetherform a bar code.
 40. The package of claim 38, in which the tray has awindow formed in its bottom, the first component additionally comprisesan absorbent liner that is dimensioned to fit in the tray in apredetermined position relative to the window, and the first substrateis attached to the bottom of the liner in alignment with the window whenthe liner is in the predetermined position.
 41. The package of claim 40,in which the second substrate is aligned with the window and the firstsubstrate.
 42. The package in claim 41, in which the second substrate isopaque and has one or more cutouts and the one or more visual elementsof the first substrate are visible through the one or more cutouts. 43.A method for packaging a food product subject to contamination, themethod comprising the steps of: printing one or more visible contaminantindicating elements on a first substrate with a material that visiblychanges when subjected to a pathogen or toxin to be detected; placingthe first substrate in a food tray; placing the food product in thetray; wrapping the tray and the product in a sheet of transparentmaterial so that first substrate is visible; printing a plurality ofvisible product identifying elements on a second substrate; and applyingthe second substrate to the exterior of the sheet in alignment with thefirst substrate without hiding the one or more pathogen or toxinindicating elements.
 44. The method of claim 43, in which the step ofplacing the first substrate in a food tray comprises attaching the firstsubstrate to one surface of an absorbent liner and placing the onesurface of the liner in contact with the bottom of the tray in apredetermined position and the method additionally comprises the step offorming a window in the bottom of the tray in alignment with the firstsubstrate.
 45. A food contamination detection system comprising; a firstbar code symbol coded to identify a food product when contamination isnot present; a second bar code symbol coded to identify contaminatedfood when contamination is present; means for altering said bar codessuch that, when contamination is not present the first bar codeidentifies the food product and when contamination is present the secondbar code identifies the presence of contamination.
 46. The foodcontamination system of claim 45 wherein said means for altering saidbar codes comprises an antibody.
 47. The food contamination system ofclaim 46 wherein said antibody is attached to a label.
 48. The foodcontamination system of claim 47 wherein said label comprises animmunobead.
 49. The food contamination system of claim 47 wherein saidlabel comprises a colored immunobead.
 50. A dual bar code system fordetecting contamination in food comprising: an indicator which changescolor when contamination is present; a first bar code symbol coded toidentify a food product having an indicator area for changing theappearance of said first bar code; and a second bar code symbol coded toidentify food contamination having an indicator area for changing theappearance of said second bar code; wherein when food contamination ispresent, the appearance change of the first bar code precludes productidentification, and the appearance change of the second bar codeidentifies the presence contamination.
 51. The dual bar code system ofclaim 50 wherein said indicator comprises a chemical.
 52. The dual barcode system of claim 50 wherein said indicator comprises an antibody.53. The dual bar code system of claim 52 wherein said antibody comprisesa monoclonal antibody.
 54. The dual bar code system of claim 53 whereinsaid antibody is attached to a label.
 55. The dual bar code system ofclaim 54 wherein said label comprises an immunobead.